#!/usr/bin/env ruby

# This script formats the output of the `git diff <old_rev> <new_rev> --raw`
# command so it can be processed by `git cat-file`

# We need to convert this:
# ":100644 100644 5f53439... 85bc2f9... R060\tfiles/js/commit.js.coffee\tfiles/js/commit.coffee"
# To:
# "85bc2f9 R\tfiles/js/commit.js.coffee\tfiles/js/commit.coffee"

ARGF.each do |line|
  _, _, old_blob_id, new_blob_id, rest = line.split(/\s/, 5)

  old_blob_id.gsub!(/[^\h]/, '')
  new_blob_id.gsub!(/[^\h]/, '')

  # We can't pass '0000000...' to `git cat-file` given it will not return info about the deleted file
  blob_id = new_blob_id =~ /\A0+\z/ ? old_blob_id : new_blob_id

  $stdout.puts "#{blob_id} #{rest}"
end